Method and apparatus for determining the length of single-walled carbon nanotubes
The present invention is directed to at least one method and at least one apparatus for determining the length of single-wall carbon nanotubes (SWNTs). The method generally comprises the steps of: dispersing a sample of SWNTs into a suitable dispersing medium to form a solvent-suspension of solvent-suspended SWNTs; determining the mean SWNT diameter of the solvent-suspended SWNTs; introducing the solvent-suspended SWNTs into a viscosity-measuring device; obtaining a specific viscosity for the SWNT solvent-suspension; and determining the length of the SWNTs based upon the specific viscosity by solving, for example, the Kirkwood-Auer equation corrected by Batchelor's formula for the drag on a slender cylinder for “L,” to determine the length of the SWNTs. The apparatus generally comprises: a SWNT sample introduction mechanism; a dispersal chamber; a SWNT radius-determination chamber; and a viscosity determining chamber, wherein the SWNT sample introduction mechanism, the dispersal chamber, the SWNT radius-determination chamber, and the viscosity determination chamber are each operatively connected to at least one of the others.
1. A method for determining the length of single-wall carbon nanotubes comprising the steps of:
(a) dispersing a sample of SWNTs into a suitable dispersing medium to form a solvent-suspension of solvent-suspended SWNTs;
(b) obtaining the mean SWNT diameter of the solvent-suspended SWNTs;
(c) introducing the solvent-suspended SWNTs into a viscosity-measuring device;
(d) obtaining a specific viscosity for the SWNT solvent-suspension; and
(e) determining the length of the SWNTs based upon the specific viscosity.
2. The method of claim 1 , further comprising a step of evaluating whether the solvent-suspended SWNTs are dispersed individually.
3. The method of claim 2 , wherein the step of evaluating is done using fluorescence measurements.
4. The method of claim 1 , wherein the step of dispersing comprises the use of a surfactant.
5. The method of claim 1 , wherein the step of dispersing comprises a dispersing technique selected from the group consisting of polymer wrapping, chemical derivatization, acid protonation, and combinations thereof.
6. The method of claim 1 , wherein the step of dispersing comprises chemical derivatization selected from the group consisting of sidewall functionalization, end functionalization, and combinations thereof.
7. The method of claim 1 , wherein the step of dispersing involves ultrasonication.
8. The method of claim 1 , wherein the step of obtaining the mean SWNT diameter involves a technique selected from the group consisting of Raman spectroscopy, scanning probe microscopy, electron microscopy, electron diffraction, X-ray diffraction, luminescence spectroscopy, and combinations thereof.
9. The method of claim 1 , wherein the viscosity-measuring device is a capillary viscometer.
10. The method of claim 9 further comprising a step of standardizing the capillary viscometer.
11. The method of claim 1 , wherein the viscosity-measuring device is a rheometer.
12. The method of claim 1 , wherein the step of determining the length of the SWNTs comprises solving KAB for rods for “L.”
13. An apparatus for determining the length of SWNTs comprising:
(a) a SWNT sample introduction mechanism;
(b) a dispersal chamber;
(c) a SWNT radius-determination chamber; and
(d) a viscosity determining chamber, wherein the SWNT sample introduction mechanism, the dispersal chamber, the SWNT radius-determination chamber, and the viscosity determination chamber are each operatively connected to at least one of the others.
14. The apparatus of claim 13 , wherein the dispersal chamber provides solvent-suspended SWNTs.
15. The apparatus of claim 13 , wherein the dispersal chamber utilizes ultrasonication to disperse SWNTs.
16. The apparatus of claim 13 , further comprising a dispersion evaluation chamber operatively connected to at least one of the SWNT sample introduction mechanism, the dispersal chamber, the SWNT radius-determination chamber, and the viscosity determination chamber.
17. The apparatus of claim 16 , wherein the dispersion evaluation chamber utilizes luminescence spectrosopy to provide verification of SWNT dispersion as individual SWNTs.
18. The apparatus of claim 13 , wherein the radius-determination chamber utilizes a technique selected from the group consisting of Raman spectroscopy, scanning probe microscopy, electron microscopy, electron diffraction, X-ray diffraction, luminescence spectroscopy, and combinations thereof, to determine the mean radius of the SWNTs in the sample.
19. The apparatus of claim 13 , wherein the viscosity determining chamber comprises a viscosity measuring device selected from the group consisting of a capillary viscometer, a rheometer, and combinations thereof.
20. The apparatus of claim 13 , further comprising a computer operatively connected to at least one of the SWNT sample introduction mechanism, the dispersal chamber, the SWNT radius-determination chamber, the viscosity determination chamber, and the dispersion evaluation chamber such that it can receive a viscosity measurement, wherein the computer is operable to determine the length of the SWNTs based upon the viscosity measurement.
21. A method for determining the relative length of single-wall carbon nanotubes comprising the steps of:
(a) dispersing a sample of SWNTs into a suitable dispersing medium to form a solvent-suspension of solvent-suspended SWNTs;
(b) introducing the solvent-suspended SWNTs into a viscosity-measuring device;
(c) obtaining a viscosity for the SWNT solvent-suspension; and
(d) comparing the viscosity to viscosities obtained for other SWNT solvent-suspensions.